CreateQuery tab (children 3)
 Identifier tab
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration x.a (children 1)
    DataType Array (children 1)
     ExpressionList (children 1)
      DataType String
   ColumnDeclaration x.b.first (children 1)
    DataType Array (children 1)
     ExpressionList (children 1)
      DataType Array (children 1)
       ExpressionList (children 1)
        DataType UInt32
   ColumnDeclaration x.b.second (children 1)
    DataType Array (children 1)
     ExpressionList (children 1)
      DataType Array (children 1)
       ExpressionList (children 1)
        DataType String
 Storage definition (children 2)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList
